Why Chickens lay soft-shelled eggs

Chickens need a lot of calcium to create good, hard shells, so most incidences of
shell-less eggs in an adult hens are related to not having enough calcium in the
diet. Young hens may lay a shell-less egg or two right as they begin to lay eggs
for the first time, before their systems have "gotten into the groove" of laying. If
your girls are on a proper diet of lay ration and have oyster shell free choice, they
should have all the calcium they need. They also need Vitamin D and a proper
balance of other vitamins so they can process the calcium. Lots of snacks or
scraps can throw off the nutrient balance of their diets or give them too much salt.

Disturbances at night while they are sleeping-a predator prowling around, or a big
storm, for example-- can also sometimes upset their system and cause shell-less
eggs. If that is what's happening, some of the other girls' eggs may have bands or
"checks" on them, as the laying process was disturbed briefly before resuming its
normal course. If disturbances are the problem, when they cease, the shell
problems should cease, too.

Another possibility has to do with the salt in their diet. Too much salinity can cause
shell-less or thin-shelled eggs. So, sometimes if they are drinking water that is
highly softened, it can contain a problem amount of salts for them.

It could also simply be a defective shell gland; it that is the case there is nothing to
be done about it.

Lastly, infectious bronchitis can also cause thin shelled eggs, or eggs with no
shells. Chances are good you would have noticed respiratory symptoms. If you
suspect your chicken has a case of IB, you should get her to a vet for a diagnosis
immediately. There are some other illnesses, such as egg drop syndrome, that
could cause the same thing. If you have eliminated everything else, your vet may
be able to help you.
Rare and Heritage poultry